Hacker News Reader

Comment by cyberax | Hacker News Reader

It's already widely known. Here in Seattle all the outdoor HVDC chargers are now down, with the cables cut.

Would we be able to insulate sufficiently for a new generation of DC fast charging where voltage is so much higher that current is so much lower that the cable isn't thick enough to be worth stealing? Could eliminate active cable cooling, as well.

I guess the problem would be stepping it back down inside the car to match the battery voltage, which is an AC endeavor, at which point it might as well just be AC grid power delivered to the car (albeit high/primary voltage, not residential/secondary voltage), and we're back to the car having enormous equipment on board that ought to be stationed, so no.

Stepping up the voltage for DC power makes the overcurrent protection insanely expensive, there is no ‘zero point’ for DC like there is for AC so circuit breakers are tricky to manufacture. Maybe fuses would work, I’m not entirely sure.

You’d be better off replacing the charger cables, in my best estimation.

AFAIK you can’t charge a battery with AC current, you’d need an inverter onboard the vehicle to convert to DC.

Junkies get about $50 per cable, apparently. The scrap value is already low.

It's just that property crimes are not prosecuted around here. So there's no downside for thieves.

They're switching to aluminum cables, with a much lower scrap value.

AC into the battery? Or did I misunderstand?

I neglected to mention rectifying, but to clarify I meant that the process of stepping down wants to be AC, not that the battery wants AC.

DC fast charging is already 500-800volts- so 125A max for 100kW, only they liquid cool the lines so you're not trying to plug in a big floppy... 4/0awg... anyway, its mostly a water/liquid jacket- not copper.

Most DCFC cables are not watercooled. A typical 175 kW / 350 kW (400 V and 800 V, respectively) DCFC cable spec is 4x50 + 1G35 + 3x 2x 1, so around 250 mm² of copper, about 2.5 kg/m. They're usually around 4 m long (exterior to the dispenser), let's say five bucks per kg, so 2.5 * 4 * 5 = 50 bucks each. Most chargers have two cables, so 100 bucks. I'm guessing the methhead bringing them to the scrap fence/yard gets like 15 bucks for having caused around 10k in property damage.

Though in many of these cases the cables are not actually stolen. People just cut them off and throw them in the bushes or don't even bother moving them. In those cases the motivation is obviously anti-EV vandalism.

I’ve never seen a DC ampacity table but #1 wire is all you need for 125A of AC current (assuming 75 degree rated terminals)

Instead of re-engineering complicated systems to be resilient to thieves, what if we just got rid of the thieves?

That's an even more complicated system. How would we catch them without the type of surveillance or anti-fencing measures that have even more downsides than the amount of theft they eliminate?

We could easily detect damage and dispatch law enforcement.

Maybe the solution is “Tesla Coil” quick charging stations for Teslas.

Instead of a cable, an electric bolt of air-cooled plasma wirelessly charges the car.

(/s)

Reply on news.ycombinator.com